Such a measuring device is known for example from the printed document U.S. Pat. No. B2-6,838,157.
The use of integrated thermocouples for temperature measurement on gas turbine blades without a surface coating has long been known (see for example U.S. Pat. No. 3,592,061).
The blades in the first stages of modern gas turbines, which are exposed to increasingly higher hot-gas temperatures to increase efficiency, are provided on the surface with a special protective surface coating (heat insulating layer or Thermal Barrier Coating TBC), which is intended to protect the underlying metal of the base element from excessively high temperatures. For normal operation (base load), the influence of the thermal barrier coating in the heat transfer models is well understood. In the part-load range, however, the effect of the thermal barrier coating decreases, since the boundary conditions for heat transfer change. Together with the lower pressures in the cooling air supply in the case of part-load, this can lead to a restriction of the service life of the blading.
The existing instrumentation with thermocouples relates to blades without a thermal barrier coating, in order to eliminate the influence of the thickness and the thermal conductivity of the thermal barrier coating in the validation of the cooling in base-load operation. In order to permit validation also in part-load operation, technology with which temperature measurement under the thermal barrier coating can be realized (by means of thermocouples) is necessary.
In the document mentioned at the beginning, it has already been proposed to arrange temperature sensors “buried” in gas turbine components provided with thermal barrier coatings (see for example the sensor 78 in FIG. 2 of U.S. Pat. No. B2-6,838,157), in that a trench is first made in the ready-coated component, the trench is then lined with an insulation, a conducting layer is subsequently deposited on the bottom of the trench, an insulating layer is applied thereover, and finally the trench is filled again to the surface of the thermal barrier coating (FIG. 3).